Various symptoms of skin aging are caused by aging, sunlight (ultraviolet radiation) exposure, eating habits, stresses, etc. Retarding skin aging is an important health and aesthetic objective. In particular, among the symptoms of skin aging, melasma and freckles can be serious aesthetic concerns for women. The developmental mechanism of melasma and freckles in the skin has not been fully elucidated yet. In general, however, it is considered that melasma and freckles are caused by the deposition of melanin pigments in the epidermis, which are produced in skin cells due to stimuli such as ultraviolet radiation, etc.
Conventionally, external cosmetic preparations comprising substances which have efficacy as a whitening agent such as ascorbic acid and its derivatives, glutathione, kojic acid, arbutin, cysteine, etc. are used for the decrease and treatment of pigmentation such as melasma and freckles. However, such agents for external application are slow in ameliorating pigmentation and their effects are not satisfactory.
Considering such drawbacks of the prior art, the development of means for retarding skin aging, particularly means for efficiently ameliorating pigmentation, has been desired.